Ultralong-LifetimePhosphorescent Carbonized PolymerDots Enabled by Synergistic Cross-Link-Enhanced Emission and RigidMatrix Protection for Latent Fingerprint Visualization and InformationEncryption

Abstract Compared with traditional inorganic phosphors, carbon polymer dots (CPDs) generally display weak phosphorescence intensity, mainly because nonradiative decay pathways induce quenching of triplet excited states and thus restrict their practical applications. To suppress phosphorescence quenching originating from nonradiative transitions, we developed a synergistic strategy integrating cross-link-enhanced emission (CEE) and the rigid matrix confinement effect of B2O3 to fabricate ultralong-phosphorescent CPDs composites. Herein, aspartic acid and boric acid were used as precursors to prepare control sample CPDs-200 at 200 °C, while CPDs-200-MPD was prepared at 200 °C by adding m-phenylenediamine (MPD) to the precursor system. Carboxyl groups of aspartic acid underwent cross-linking with amino groups of MPD under heating, followed by carbonization. Confined within the B2O3 matrix, nonradiative losses were drastically suppressed, yielding green phosphorescence with an ultralong naked-eye afterglow of 20 s. Compared with CPDs-200, the phosphorescence intensity of CPDs-200-MPD increased by 8-fold, a 3 s phosphorescent afterglow can still be visualized under ambient lighting. Finally, CPDs-200-MPD was successfully applied to fingerprint detection and information encryption.